Cushioning shoe insole with plural, differentiated surface-tension cushioning

ABSTRACT

A shoe insole structure which includes a singular (or plural) acceleration-rate-sensitive, differentiated-softness, bonded viscoelastic cushioning layer(s), joined to the upper surface of which is a low-surface-friction, moisture-wicking fabric overlayer. The overall insole presents to a foot an effective upwardly facing support surface which has an effective surface tension which is lower than (differentiated from) that of the underside of the foot.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation from regular U.S. patentapplication Ser. No. 10/003,122, filed Nov. 14,2001 for “Cushioning ShoeInsole”, which application, as does this continuation application also,claims priority to U.S. Provisional Application Serial No. 60/281,604,filed Apr. 4, 2001 for “Cushioning Shoe Insole”. Both of thesepredecessor and serially copending patent applications are herebyincorporated into this application by reference.

BACKGROUND AND SUMMARY OF THE INVENTION

[0002] This invention relates to a new and advantageous shoe insole, andin particular to an insole which is usable in a medically-relatedenvironment as, for example, where shoewear is prescribed or recommendedfor various medical conditions requiring special uniform and highlytopographically conformal cushioning to minimize singular high-pressurepoints applied to the underside of the foot. Especially, the inventionproposes an insole structure that provides (a) superior shock-absorbingqualities, (b) reliable, intimate thermo-conformation (spatialconformation) to the topography of the underside of the foot, (c)efficient moisture wicking and related cooling, and (d) avoidance ofuncomfortable, “hard landing” “bottoming out” of the foot within a shoeduring walking.

[0003] According to a preferred embodiment of the invention, theseimportant performance behaviors are achieved in an insole structurewhich preferably is layered in nature, and which includes a cushioninglayer structure that carries a bonded overlayer of alow-surface-friction, moisture-wicking fabric material, which material,collectively with the cushioning layer structure, presents to theunderside of the foot an effective support surface which exhibits aneffective surface tension which is less that the surface tension of theunderside of the foot. Such a differentiated surface-tension conditionhas the important effect of promoting close, topographic, cushioningconformation to the underside of the foot, with the important result ofoffering a high level of cushioning (softness) comfort. Additionally,where, as is especially proposed by the present invention, thecushioning layer structure therein is formed of anacceleration-rate-sensitive material which is slow to restore itselffrom a deformed condition, under-foot topographic conformation issignificantly enhanced.

[0004] There are a number of different ways in which an appropriate andsuccessful cushioning layer can be constructed and implemented. One suchsuccessful way involves a single cushioning layer formed of a uniformlycharacterized acceleration-rate-sensitive material with one softnessbehavior nature appropriately surface-covered at the surface intend forfoot engagement with a low-surface-tension moisture-wicking fabric.

[0005] Another way involves the use of plural, stacked cushioning layersof such acceleration rate-sensitive materials, each having a differentsoftness behavior, and stacked in a softness-progression manner whereby,as between two vertically adjacent layers, the softer one of the two isthe upper layer. Here, too, an overlayer of moisture-wicking fabric isemployed.

[0006] Still another approach involves employing a single suchcushioning layer which is prepared with an internally varying softness,with the softer regions disposed in the layer above the firmer regions.A moisture-wicking ovelayer is also employed in this version of aninsole constructed in accordance with the invention.

[0007] In all embodiments and versions of the invention, the effectivesurface tension of the uppermost surface region of the insole ispreferably less than that of the underside of the usual human foot.

[0008] The various features and advantages that are offered by theinsole construction proposed by this invention will become more fullyapparent as the description which now follows is read in conjunctionwith the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 is a simplified top plan view illustrating an isolated,left-foot, cushioning shoe insole which is constructed in accordancewith one embodiment of the present invention.

[0010]FIG. 2 is an enlarged, fragmentary side elevation taken generallyalong the line 2-2 in FIG. 1.

[0011]FIG. 3 is a view somewhat like that presented in FIG. 2, generallyillustrating how the insole of FIGS. 1 and 2 provides anti-spring-like,differentiated-softness, cushioning and shock absorbing in accordancewith the present invention.

[0012]FIG. 4 is a view much like FIG. 2, except that FIG. 4 shows amodified form of the invention in which the cushioning layer structureincludes plural layers, and specifically two layers.

[0013]FIG. 5 is an enlarged, fragmentary cross-section taken generallyalong the line 5-5 in FIG. 4.

[0014]FIG. 6 is a view which is very similar to that presented in FIG.5, except that here what is shown is a modified form of the invention inwhich the shoe insole of this invention possesses a unidirectional,lateral taper defining a high lateral side and a low lateral side.

[0015] It should be understood that components illustrated in the insoleof this invention in FIGS. 1-6 inclusive are not necessarily representedtherein to scale.

DETAILED DESCRIPTION OF THE INVENTION

[0016] Turning now to the drawing figures, one of the embodiments of theproposed insole structure of this invention is indicated generally at10. For the purpose of convenience herein, insole 10 is pictured anddescribed in a form wherein it is employable as a free insert for analready constructed shoe. It should be understood, however, that theinsole of this invention could easily be incorporated as a part ofinitial shoe construction.

[0017] Insole 10 includes a heat-flowable, anti-spring-back,acceleration-rate-sensitive cushioning layer structure 12 formedpreferably of a material such as the microcdellular, viscoelastic,urethane material known as PORON® 400 Performance Urethane, Series 90,Formulation #94, manufactured by Rogers Corporation in Woodstock, Ct.

[0018] Layer structure 12, formed as just described, has ashock-cushioning behavior whereby (a) it deforms in anacceleration-rate-sensitive manner (the greater the acceleration, theslower the responsive deflection), and (b) returns slowly from such adeformation toward an undeformed condition without exhibiting anyappreciable spring-like mannerisms. By the way of contrast, anundesirable spring-action response to a deflection occurs where amaterial effectively reacts to, and tends to return from, a force impactdeflection condition with a felt return force, and in a time-frame, thatgenerally match those of the event which has produced the subjectdeflection. A non-spring-like response, which is characteristic of layerstructure 12, takes the form of a return (from a shock-force/impactdeflection) that is retarded over time, and characterized by a lowered,overall-felt, return-force behavior. In a sense, a material behaving ina non-spring-like manner tends to “creep” back toward an undeformedcondition. This is how layer structure 12 behaves in insole 10.

[0019] Another important advantage which is offered by layer structure12, formed with materials like those mentioned above, is that it tendsto flow (at a creep) with heat and compression, and thus tends to deformgradually to create an upwardly facing, topographically-conforming,foot-support surface which tends to complement and “follow” theconfiguration of the underside of a supported foot.

[0020] Suitably surface-bonded (as by an appropriate hot-melt adhesive)to the upper surface of layer 12 is a thin, fabric, moisture-wicking,low-surface-friction and abrasion-wear layer structure, or layer, 14.Preferably, layer 14 is formed of a woven-fibre fabric material, such asthat material known as HEATERSTONE®, made by Lee Fashion Fabrics, inGloversville, N.Y. Fabric layer 14 herein has a thickness preferably ofabout {fraction (1/64)}-inches, and includes elongate, stretch-resistantfibres (see 14 a in the figures) that function as tension-active,load-distributing components in the fabric.

[0021] Layer 14 plays several important roles (i.e., cooperative withlayer structure 12) in insole 10. One of these involves furnishing awear surface to protect the longevity of the underlying cushioninglayer, and to do so without appreciably diminishing the cushioning andshock-absorbing capabilities of that layer. Another involves furnishinga surface which has a low coefficient of sliding friction, so as tominimize friction heat which develops around the foot of a user duringnormal shoe use. A third important function for this layer is that itwicks moisture which typically develops in a shoe, and caries thismoisture efficiently to the side edges (perimeter) of the insole, wherethat moisture can quickly evaporate, and in so doing, provide coolingwithin a shoe. A fourth significant function of layer 14 is that itsfibres act as elongate load-distributing elements that aid in spreadinglocalized load events to a broader area within insole 10.

[0022] Layers 12, 14 collectively present to the underside of a foot asurface tension characteristic which is less than that of theundersurface of a foot, whether or not the foot is covered by a sock.

[0023] As was pointed out above, the materials which make up cushioninglayer structure 12 respond to shock-force/impact loading in such afashion that this structure has a tendency to return from a deformation(produced by such loading) in a retarded, slow and low-return-force(non-springy) fashion. This “low return-force” behavior is evidenced bythe material returning toward an undeformed (unshockdeformed) conditionwithout displaying anywhere near the same level of local return force orpressure which characterizes the initial loading per se.

[0024]FIG. 3 is presented to highlight this important performance oflayer structure 12 in insole 10. In solid lines in this figure,structures 12, 14 are shown representationally shock-deflected toproduce the combined deformation generally indicated as a depression atD. Dash-double-dot lines show the undeformed “prior” dispositions of thelocal upper surfaces of these two layer structures.

[0025] Short, solid downwardly-pointing arrow Ti, and long, shaded,downwardly-pointing arrow Fi represent related time-span andapplied-force characteristics respectively, of the shock event which hasproduced deformation D. Long, solid, upwardly-pointing arrow T2, andshort, shaded, upwardly-pointing arrow F2, represent the relatedtime-span and return-force characteristics, respectively, of how layerstructure 12, in cooperation with layer structure 14, will try to returnfrom the shock-deformed state. As can be seen, T2 is greater in lengththan is T1, and F1 is greater in length than is F2. These comparativeand differentiated “lengths” represent the differentiated time-span andforce-level behavior characteristics which characterize the kind ofnon-spring-factor cushioning response that produces, respectively, theremarkable shoe-cushioning performance offered by the present invention.Fibres 14 a, as indicated by reverse arrows in FIG. 3, cooperatively actto distribute and spread load laterally in the insole.

[0026] The several outwardly pointing arrows which radiate from theletter M in FIG. 1 represent how moisture is wicked by layer 14 to thelateral (perimetral) edges of insole 10—the perimeter of the insole. Atthe perimeter of the insole such wicked moisture readily evaporates, andintroduces effective and noticeable cooling in a shoe equipped with theinsole.

[0027] Turning attention now to FIG. 4, here there is shown at 20 amodified form of insole which is made in accordance with the presentinvention. Insole 20 includes a heat-flowable, anti-spring-back, shock(acceleration)-rate-sensitive cushioning underlayer structure (or layerstructure) 22, including upper and lower, suitably bonded-together,material layers 22 a, 22 b, respectively. Each of layers 22 a, 22 b isformed preferably of a material like that employed for previouslydescribed layer structure 12. Upper layer 22 a is softer than layer 22b, and preferably is also thicker than layer 22 b.

[0028] In insole 20, layer 22 a is specifically formed of PORON® productnumber SRS-15188-47-54U-RR, and layer 22 b of PORON® product numberSRVF-15118-42-54U-RR. Also, and while different relative dimensions canbe employed for these two layers, in the embodiment pictured in FIG. 4,layers 22 a, 22 b have uniform, though different, distributedthicknesses (see also FIG. 5). The thickness of layer 22 a, the upper,softer layer, is about 4-mm, and that of lower, firmer layer 22 b isabout 3-mm. Thus the overall cushioning layer structure 22 herein can bethought of as having, from top surface to bottom surface, a spatiallyvaried softness characteristic which progresses from softer towardfirmer downwardly through this layer structure. It will become apparentto those skilled in the art that different useful structural approachescan be employed to create such a varied softness/firmness layerstructure.

[0029] Mentioning some of these useful ways in which variations in thiscushioning layer structure can be made, layer 22 a could be the samethickness as, or thinner than, layer 22 b. The absolute, and relative,softnesses of these layers could be varied. Further, layer structure 22could include more than two viscoelastic layers, or perhaps it could beinfinitely graded.

[0030] Bonding between layers 22 a, 22 b, preferably created by anysuitable contact adhesive, produces a certain level of interfacialtelegraphy of the individual properties of each layer to the other, andthis bonding contributes to the overall performance of the insole.

[0031] Suitably joined to the upper surface of layer structure 22 is afabric, moisture-wicking layer 24 which is like previously describedlayer 14. Layer 24 has strands 24 a which are like strands 14 a.

[0032] Turning attention now to FIGS. 5 and 6, FIG. 5 helps toillustrate the uniform thicknesses of layers 22 a, 22 b, and 24. FIG. 5pictures a modified construction for insole 10 wherein the thickness oflayers 22 a, 22 b are laterally tapered. Such tapering can be beneficialin certain instances, and can be made to “slant” in different degreesand directions, if desired.

[0033] Not specifically shown in a drawing herein is anothermodification of the invention wherein a single cushioning layer, likepreviously discussed layer 12, is formed with a varying softnesscharacteristic which graduates from softer toward firmer progressingdownwardly through the layer

[0034] The insole thus proposed by the present invention offers somevery special advantages in relation to conventional insoles. Itsconstruction is quite simple, and it lends itself readily to initialincorporation, and even retrofitting, in many otherwise conventionalshoe designs.

[0035] Heating of layer structures 12, 22 during normal use causes theupper surfaces of these layers to form-fit the underside of a user'sfoot. This is a very important feature of the invention where insoles10, 20 are employed in a medical situation. The described behavior,strongly contributed to by the fact that the effective surface tensionof the upper engagement surface of the insole is less than that of theunderside of the usual foot, causes these insoles to form-fit veryclosely to the underside of the foot, and this performance minimizeshigh-pressure points of contact with the foot. Accordingly, the insoleof this invention promotes good blood circulation.

[0036] Wicking of moisture by layers 14, 24 promotes cooling, and thisis important in various medical situations, such as in a diabetessituation.

[0037] Acceleration-rate-sensitivity in layer structures 12, 22 leads tosignificant anti-springback behavior, and contributes to a remarkableability of the insole of the invention to cushion shock loads. Alsofabric layers 14, 24 act as low-friction, abrasion-resistant uppersurfaces in the insoles, protecting layer structures 12, 22 from undueearly wear, and minimizing friction-induced heat build-up as the footnaturally moves around in a shoe.

[0038] Accordingly, while preferred embodiments and certainmodifications have been illustrated and/or described herein, othervariations and modifications may be made within the scope of theinvention.

We claim:
 1. A cushioning insole structure for a shoe, which structurepresents to a foot an effective support surface having a surface tensionwhich is less than that of the underside of the foot, said insolestructure comprising a cushioning layer structure having upward andlower surfaces, and formed of a material which, following deformation,tends to return naturally to an undeformed condition at a rate which isslower than the rate at which it was deformed, and alow-surface-friction, foot-engaging, moisture-wicking layer joined tothe upper surface of said cushioning layer structure, said cushioninglayer structure and said moisture-wicking layer collectively presentingto the underside of a foot a support surface which exhibits effectivelya lower surface-tension characteristic then that of the foot underside.2. The insole structure of claim 1, wherein said cushioning layerstructure is formed from a non-springy, acceleration-rate-sensitive,cushioning and shock-absorbing material.
 3. The insole structure ofclaim 2, wherein said acceleration-rate-sensitive material is aviscoelastic material.
 4. The insole structure of claim 1, wherein saidcushioning layer structure is characterized by a structural deformationcushioning nature which varies from softer toward firmer progressingdownwardly through the layer structure from its said upper surfacetoward its said lower surface.
 5. The insole structure of claim 4,wherein said cushioning layer structure is formed by at least a pair ofdifferentiated-softness, structural cushioning materials disposed one(upper) above the other (lower), and bonded to each other, with theupper cushioning material being softer than the lower cushioningmaterial.
 6. The insole structure of claim 5, wherein each of saidmaterials within said cushioning layer structure is formed from anon-springy, acceleration-rate-sensitive, cushioning and shock-absorbingmaterial.
 7. The insole structure of claim 6, wherein saidshock-absorbing material is a viscoelastic material.